Mass (mass spectrometry)
From Mass Spec Terms
Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. It is a central concept of classical mechanics and related subjects.
The symbol for the physical quantity mass is m.
The SI unit for mass is kg. In mass spectrometry it is more common to use the Atomic Mass Unit u, which is also called dalton Da.
In spite of their name, mass spectrometers do not measure the mass of ions, but the mass/charge ( m/q) of ions.